The present invention relates to a data recording instrument and more particularly to a data recording instrument for recording an environmental variable.
When goods of any kind are handled and moved in shipment, the possibility exists that they may be damaged as a result of change in an environmental variable such as temperature, impact or humidity from the beginning of the trip to its destination. Certain goods are damaged when the temperature of the environment in which they are transported changes beyond certain limits. Other types of cargo are particularly sensitive or fragile and as a consequence of mishandling, abuse, accident, excess impact, drifting of the cargo or the like, damage may occur. Of course the sensitivity or fragility of the particular goods involved determines the extent to which they can withstand or remain unaffected by various magnitudes of impact shock forces.
The damage created by excessive changes in a particular environmental variable are frequently not visible or immediately ascertainable by the receiver, particularly when the goods are delivered packaged and neither the shipper or the freight forwarder is aware of the occurence of any improper variance in a particular environmental variable. When the injury or damage to the goods is finally discovered by the purchaser controversies may arise as to whether the shipper, the freight forwarder, or the customer is responsible for the damage.
In order to remove or minimize the uncertainty as to who shall be the responsible or liable party in the above described circumstances, shippers have increasingly adapted the utilization of some form of indicating, monitoring or recording device which will provide evidence of the occurence of a change in an environmental variable which will possibly damage the goods. Data recording instruments for recording an environmental variable on a strip chart are presently being used by shippers from the time that it leaves the shipper until it is received by the purchaser.
The prior art strip chart data recording instruments have utilized a manually wound or battery powered strip chart motor for moving the strip chart past a sensor at a predetermined rate of speed. The sensor marks the environmental variable on the strip chart as it passes thereunder. Thus, a record is made of the environmental variable on the strip chart and if there is any change in the environment that would damage the goods shipped, it is recorded on the strip chart and the time of the occurence would also be indicated. Accordingly, the responsibility for damage to the goods is readily ascertainable upon inspection of the strip chart.
One such prior art strip chart data recording instrument is disclosed in Johnson, U.S. Pat. No. 3,787,885. Johnson discloses a strip chart recorder which has a disposable strip chart dispenser. The dispenser holds one rolled end of the strip chart and the free end passes over a writing surface and beneath a window exposing the strip chart above the writing surface. The free end of the strip chart coming out of the dispenser is secured to a drive spool which is powered by a battery driven motor. When the battery driven motor is activated, the drive spool is rotated to thereby rotate the drive spool and correspondingly advance the strip chart at a predetermined rate of speed. The drive spool is mounted independent of the dispenser and the strip chart may readily be removed from the drive spool after use of the strip chart data recording instrument.
As pointed out above the primary reason for using a data recording instrument is to determine whether or not goods are damaged in shipment due to the change in an environmental variable and if so determine who shall be the responsible or liable party for that damage. It is important therefore, that after the data recording instrument is used, the strip chart may not be tampered with or altered or changed. On the other hand the data recording instrument must allow the strip chart to be removed from the data recording instrument after use so that the data recording instrument may be used again. In addition, the strip chart should be available for inspection after the goods are shipped to determine whether any damage occured to the goods in shipment as a result of a change in an environmental variable.
It is also desirable to provide a sensor in the data recording instrument that is adjustable so that depending on the level of the environmental variable to be sensed, the sensor may be adjusted accordingly. For example, it is desirable to ship certain goods in a certain range of tempertures. Accordingly, it is desirable to adjust the marker of the temperature sensor so that it will move between the predetermined range of temperatures and will accordingly record any change in the environmental temperture.